1. Field of the Invention
The present invention relates to an air battery.
2. Description of Related Art
An air battery is known as means for storing and efficiently using electric energy. In the air battery, it is not necessary to arrange a positive electrode active material in a battery case, and a negative electrode active material can be arranged in most of the internal region of the battery case. Therefore, the air battery has a characteristic in that, in principle, high energy density can be obtained. That is, the air battery can realize high capacity and thus has attracted much attention.
In an air electrode of the air battery, a catalyst which oxidizes and reduces oxygen is used. As the air electrode of the air battery, for example, Japanese Patent Application Publication No. 2014-93227 (JP 2014-93227 A) discloses an air electrode for an air battery. This air electrode for an air battery contains at least a conductive material and an inorganic fluoride in addition to a catalyst for an air battery. For example, a perovskite type oxide containing transition metal is used as the catalyst for an air electrode, and a carbon material is used as the conductive material.
In order to use the air battery as a rechargeable secondary battery, for example, a method of using an air electrode during discharging and using an auxiliary charging electrode during charging may be used. However, in this case, the advantageous effect that it is not necessary to arrange a positive electrode active material in a battery case deteriorates due to the arrangement of the auxiliary charging electrode. Therefore, a technique capable of charging and discharging using one air electrode without using an auxiliary charging electrode is desired.
In the air battery disclosed in JP 2014-93227 A, for example, a combination of materials including a specific perovskite type oxide, a carbon material, and an inorganic fluoride is selected, and an air electrode formed of this combination of materials is used. When an air battery is charged and discharged using one air electrode, there is no problem in the air electrode during discharging; however, the carbon material of the air electrode may be oxidized and decomposed during charging, that is, during an oxygen evolution reaction. As a result, catalytic activity and output characteristics deteriorate. In an air battery capable of charging and discharging using one air electrode without using an auxiliary charging electrode, a technique capable of stably improving output characteristics is desired.